The in vitro synthesis of the J and P proteins (histidine transport components) will be attempted. The synthesis of the periplasmic J protein as a precursor will be investigated. The properties of the in vitro synthesized P protein will be studied. Interaction between the J and the P proteins will be studied; cross-linking experiments will also be performed for this purpose. The Q protein will be identified by a variety of methods. The interaction of the LAO protein with P and its competition with J will be analyzed. The regulation of histidine transport by nitrogen starvation will be studied. The involvement of other proteins, besides the J and the LAO, in an interaction with P will be investigated. Elucidation of the nature of the altered J protein with a defective interaction site will be completed. More mutants of this type will be isolated and studied. Reconstitution with wild-type and mutant J and P proteins will be attempted. A defective phage, carrying the transport operon, will be constructed. A Salmonella DNA-bank will be established and the hisP and hisQ genes cloned from it.